In relation to a visual distraction detecting apparatus, there has been proposed a technology that inhibits the visual distraction detecting apparatus from judging a visual distraction if a certain condition is satisfied. See, Japanese Laid-Open Patent Publication No. 2007-072629 (hereinafter referred to as “JP2007-072629A”). According to JP2007-072629A (see FIG. 6), if a steering angle δ is not equal to or less than a predetermined steering angle δ0 (step 100: NO), if a turn signal switch 34 is not off (step 102: NO), if a gear shift position is not a forward position (step 104: NO), or if the road is not straight (step 106: NO), then the output of a facial image camera 18 is invalidated and information concerning a facial angle θ is invalidated (step 110), thereby inhibiting the visual distraction detecting apparatus from judging the occurrence of a visual distraction. The proposed technology aims to perform various warning processes that are suitable in the case of a visual distraction (see paragraphs [0055] through [0066]).
The process of judging whether the road is straight or not (step 106) is performed by judging a road lane, in which the vehicle is traveling at present or in which the vehicle is expected to travel several seconds later, as a straight road if the curvature of the traveled road lane, which is detected based on information supplied from a white line recognizing ECU 38, is less than a predetermined curvature, or if the yaw angle of the vehicle is less than a predetermined angle (see paragraph [0058]).